1. Field of the Invention
The present invention relates to a label peeling mechanism for a continuous label strip and to a label printer apparatus using the label peeling mechanism. More specifically, the present invention relates to a label peeling mechanism by which a continuous label strip obtained by provisionally attaching multiple adhesive label pieces to the front surface of a sheet-shaped backing strip and winding the backing strip with the label pieces to a roll shape is conveyed, and the label pieces are peeled and separated from the backing strip at a predetermined position. In particular, the present invention relates to a technique with which it is possible to suppress slack in the conveyed continuous label strip.
2. Description of the Related Art
Conventionally, there has been used a label printer apparatus that uses a continuous label strip (hereinafter referred to as the “label sheet”) obtained by provisionally attaching label pieces (hereinafter simply referred to as the “labels”) to the front surface of a sheet-shaped backing strip and winding the backing strip with the labels to a roll shape, and that performs predetermined printing on each label.
As an example of a print scheme used by this apparatus, such as a thermal print scheme can be named with which a printable surface made of a thermal coloring layer is formed on the front surface of each label and printing is performed on the label by a thermal head abutted against the printable surface. After information, such as characters or a barcode, representing a trade name or a price is printed on the printable surface of the label, the label is peeled from the backing strip and is stuck on an article, such as a commodity product, through the adhesive underside thereof.
If printed labels are peeled one by one by manual work, this consumes much time and effort, and there occurs an inefficiency problem. In particular, in the case of labels for commercial use, it is required to peel many labels in a short period of time, so that if this peeling operation is manually conducted, the inefficiency problem becomes prominent.
In view of this problem, there has been devised a mechanism for automatically peeling printed labels.
Such a label peeling mechanism and a label printer apparatus provided with the mechanism are disclosed in prior art documents such as JP 11-171155 A, JP 06-40443 A, Japanese Utility Model Registration No. 3040855, Japanese Utility Model Application Laid-open No. Hei 05-86808, and Japanese Utility Model Application Laid-open No. Hei 03-75114.
FIG. 5 shows a schematic construction of a label printer provided with a conventional label peeling mechanism disclosed in the above prior art documents.
In FIG. 5, a roll-shaped label sheet Y obtained by provisionally attaching multiple adhesive labels L to the front surface of a sheet-shaped backing strip D at predetermined intervals and winding the backing strip D with the labels L is contained in a label printer P.
After the label sheet Y is drawn out, the underside of the backing strip D is abutted against a platen roller 10 serving as a first conveying unit, and the label sheet Y is nipped between the platen roller 10 and the surface of a thermal head H serving as a print unit. Then, the label sheet Y is conveyed in the direction of an arrow S1 (upward direction on the paper plane of FIG. 5).
Above the platen roller 10, a rod-shaped peeling pin 30 serving as a label peeling member that peels the labels L from the backing strip D is provided so as to extend in the widthwise direction of the label sheet Y. Then, the label sheet Y makes a U-turn around the peeling pin 30 and is conveyed in the direction of an arrow S2 (downward direction).
Obliquely below the peeling pin 30, a peeling roller 20 serving as a second conveying unit is provided so as to contact the peripheral surface of the platen roller 10 and to rotate by following rotation of the platen roller 10. Finally, the backing strip D, from which the labels L have been peeled, is nipped between the peeling roller 20 and the platen roller 10 and is discharged in the direction of an arrow S3.
Here, reference symbol F2 denotes a frame constituting a discharging opening 600, through which the conveyed backing strip D is discharged, and the like.
Next, there will be described a principle by which the labels L of the label sheet Y are peeled from the backing strip D by the peeling pin 30.
The peeling pin 30 is selected so as to have a diameter smaller than those of the platen roller 10 and the peeling roller 20, and the label sheet Y is pulled so as to make a sharp U-turn around the peeling pin 30 in the direction of an arrow S2 that is approximately opposite to the conveying direction S1. Here, a paper piece constituting each label L is thicker and stiffer than the backing strip D, so that when the conveying direction is changed and the label sheet Y makes the U-turn along the perimeter of the peeling pin 30, only the backing strip D is conveyed in the S2 direction and the labels L are peeled and separated from the surface of the backing strip D due to their own stiffness (see the broken line L′).
That is, after the label sheet Y is conveyed by the platen roller 10 in the S1 direction and is subjected to predetermined printing by the thermal head H, the backing strip D is pulled in the S2 direction from the peeling pin 30 by the platen roller 10 and the peeling roller 20. As a result, the labels L are automatically peeled from the backing strip D.
By the way, in order to prevent the labels L from strongly adhering to the front surface of the backing strip D, the surface energy of the front surface of the backing strip D is lowered by, for instance, applying a resin thereto. Consequently, when the backing strip D is nipped between the platen roller 10 and the peeling roller 20 and is pulled in the S2 direction, a skid (freewheeling) may occur on the peripheral surface of the peeling roller 20 that slidably contact the front surface of the backing strip D.
When such a skid occurs, a difference is caused between the speed, at which the label sheet Y is conveyed in the S1 direction by the platen roller 10, and the speed at which the backing strip D is conveyed in the S2 direction by the platen roller 10 and the peeling roller 20. Consequently, slack in the printed label sheet Y occurs between the platen roller 10 and the peeling pin 30, which results in an inconvenient state where the label sheet Y floats up in the direction of an arrow B as shown in FIG. 5.
As a result of the slack in the label sheet Y, there occurs the state shown in FIG. 5 where the printed label sheet Y is spaced from the peripheral surface of the peeling pin 30 and there occurs a phenomenon where there is reduced the angle at which the label sheet Y makes a U-turn around the peeling pin 30 in the S2 direction. Consequently, there occurs a problem that the labels L are not peeled by the peripheral surface of the peeling pin 30 and are conveyed along with the backing strip D in the S2 direction.
In order to prevent such peeling failure of the labels L, it is required to eliminate the slack in the label sheet Y by manually pulling the end portion of the backing strip D in the S3 direction. Alternatively, a mechanism for driving the peeling roller 20 may be additionally provided, for instance. With this construction, the peeling roller 20 is rotated at all times in the direction of an arrow K1 shown in FIG. 5 and tension is applied to the label sheet Y. In this case, however, there occurs a problem that the construction becomes complicated and the manufacturing cost is increased.